Wireless cellular communication networks are nearly ubiquitous, and provide mobile voice and data communications to millions of subscribers. In a cellular network, a fixed transceiver (base station, Node B, etc.) provides two-way radio communications with a plurality of subscribers within a geographic area, or cell (as used herein, the term sector is synonymous with cell). Methods of suppressing intra-cell radio interference, such as time-division, frequency-division, and code-division multiplexing, and combinations thereof, are known in the art. Additionally, methods of suppressing inter-cell interference, such as frequency reuse patterns, are known in the art. In modern wireless cellular communication networks, inter-cell interference remains the dominant source of performance impairment, restricting data rates, system capacity, and the quality of delivered communication services.
Coordinated multipoint (CoMP) is a technology to minimize inter-cell interference. A plurality of geographically contiguous cells—referred to as sub-cells—are grouped together to form a CoMP cell. Each CoMP cell has a central controller that coordinates transmission within its constituent sub-cells so as to minimize inter-cell interference within the CoMP cell (referred to herein as inter-sub-cell interference). The CoMP cell controller minimizes inter-sub-cell interference by coordinating scheduling of transmissions to and from user equipment (UE) within the cells, and/or actively suppressing interference using signal processing techniques.
Although the CoMP system can be effective in minimizing inter-sub-cell interference, the inter-CoMP-cell interference still exists in both the uplink and downlink along the joined areas between neighboring CoMP cells. FIG. 1 depicts a network 10 divided into three contiguous CoMP cells, identified for the purpose of discussion herein as the Red CoMP cell 12, Yellow CoMP cell 14, and Blue CoMP cell 16. The border sub-cells in each CoMP cell 12, 14, 16 are depicted as hatched lines. These border sub-cells may experience interference from transmissions in the border sub-cells of neighboring CoMP cells, as no coordination exists between the CoMP cells 12, 14, 16. In effect, the performance-limiting interference is merely pushed out toward the boundary of the CoMP cells 12, 14, 16. One hypothetical solution to this problem would be to connect all sub-cells to a single central unit, and coordinate transmissions and/or suppress interference over all cells in a network 10 simultaneously. However, this is not feasible in practice, especially for large networks.